1) a: 1-chlorobutan-2-one.
2) d: pentane-2,4-dione.
3) d: 3-oxohexanal.
4) b: 3-methybut-3-en-2-one.
5) c: 1-hydroxybutan-2-one.
6) d: 5-hydroxycyclohex-2-en-1-one.
7) c: 2-oxopropanoic acid.
8) b: cyclohexa-2,5-diene-1,4-dione.
9) c: diphenylmetanone.
10) a: 1-phenylpropan-1-one.